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Home > Products > Circuit Protection > Transient Voltage Suppressors (TVS) > TVS Diodes

Taiwan Semiconductor Corporation SMAJ40C

Name: SMAJ40C
Brand: Taiwan Semiconductor Corporation
SKU: SMAJ40C
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SMAJ40C

Manufacturer:: Taiwan Semiconductor Corporation

Category:: TVS Diodes

Package:: DO-214AC, SMA

Datasheet:: SMAJ40C.pdf

Description:: 400W, 49.4V, 10%, BIDIRECTIONAL,

Quantity:: RFQ Add To RFQ list

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Inventory:4,661

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Product details

Overview

SMAJ40C from Taiwan Semiconductor is a unidirectional 400W transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for robust overvoltage protection in DC power rails. It features a 40V working stand-off voltage (V_WM), 44.4–54.3V breakdown voltage (V_BR @ 1mA), and clamps to ≤71.4V at 5.6A peak impulse current under 10/1000μs waveform - deployed in SMPS input stages, DC/DC converters, and lighting drivers.

For engineers reviewing the SMAJ40C datasheet, SMAJ40C pinout, SMAJ40C application, or SMAJ40C equivalent, key selection criteria include its bidirectional-capable C-suffix variant designation, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, 150°C max junction temperature, and glass-passivated junction ensuring stable clamping performance across automotive and industrial environments.

Technical Context

The SMAJ40C operates as a unidirectional avalanche diode with a single-die DO-214AC construction, optimized for fast transient suppression on low-impedance DC lines. Its sub-1ps response time ensures clamping before downstream ICs experience overstress, while its 1μA max reverse leakage at V_WM minimizes standby power loss in battery-sensitive systems.

Rated for 400W peak pulse power (10/1000μs), it delivers 71.4V clamping voltage at 5.6A - validated per IEC 61000-4-2/4-4/4-5 and ISO 7637-2 test profiles. The device sustains 40A non-repetitive forward surge (8.3ms half-sine) and maintains operation from –55°C to +150°C, supporting under-hood and industrial control applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_WM	40 V - Maximum continuous reverse operating voltage before significant leakage begins; defines safe DC rail margin.
V_BR min/max	44.4 V / 54.3 V @ 1 mA - Breakdown threshold range; ensures reliable triggering above nominal system voltage.
V_C @ I_PPM	≤71.4 V @ 5.6 A - Clamped voltage during 10/1000μs surge; determines maximum stress on protected ICs.
P_PPM	400 W - Peak pulse power handling; enables protection against high-energy transients like load dump or inductive kick.
I_R @ V_WM	≤1 μA - Reverse leakage at stand-off voltage; critical for low-power and battery-backed circuits.
T_J max	+150 °C - Maximum junction temperature; supports operation in high-ambient environments without derating.
Package	DO-214AC (SMA) - Surface-mount outline with 0.060 g mass; compatible with automated placement and reflow soldering.

Pinout & Package

DO-214AC (SMA) package: molded epoxy case with matte tin-plated leads, polarity indicated by cathode band. Compliant with UL 94V-0, JESD201 Class 2 whisker resistance, and J-STD-020 moisture sensitivity level 1.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to lower-potential side of protected line; conducts during forward surge events (e.g., reverse polarity).
Cathode	Avalanche clamping terminal	Connected to higher-potential side (e.g., V_IN); initiates avalanche breakdown when reverse voltage exceeds V_BR.

Key Features

Feature	Design Value
Clamping speed	Typically <1.0 ps response from 0 V to V_BR min - prevents ESD/EFT-induced latch-up in sensitive controllers.
Power rating	400 W peak pulse (10/1000μs), derated linearly above 25°C - sustains repeated surges in automotive power modules.
Leakage control	<1 μA IR at V_WM - avoids false triggering and preserves efficiency in always-on 12 V/24 V monitoring circuits.
Standards compliance	Fully meets ISO 7637-2 Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect/connect), and Pulse 3a/3b (line transients) - certified for automotive ECUs.
Process reliability	Glass passivated chip junction - eliminates surface contamination risks and ensures long-term parameter stability under thermal cycling.

Applications

Switching Mode Power Supply (SMPS)	On-board DC/DC Converter
Use Scenario: Input stage protection against line surges and hot-swap transients in 48 V telecom rectifiers. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input capacitor and primary-side controller to clamp induced spikes before they reach PWM IC. Use Value: Limits voltage excursion to ≤71.4 V during 400 W transients, preventing gate oxide damage to MOSFET drivers and maintaining regulation integrity.	Use Scenario: Protection of 5 V/3.3 V point-of-load regulators in industrial PLC backplanes. IC Role / Device Role / Timing Role: Standoff-rated TVS on secondary-side output rail to absorb coupling noise from adjacent switching channels. Use Value: 40 V V_WM allows safe operation with 36 V nominal input, while 1 μA leakage avoids loading low-current feedback networks.
Automotive Lighting Driver	Adapter Input Stage
Use Scenario: Overvoltage suppression on LED driver inputs exposed to 12 V/24 V vehicle battery transients. IC Role / Device Role / Timing Role: Primary-line TVS absorbing load-dump pulses (ISO 7637-2 Pulse 5a) upstream of buck controller. Use Value: 400 W rating handles 120 V/100 ms load dump energy; 150°C T_J max supports under-hood mounting near headlamp assemblies.	Use Scenario: AC-DC adapter front-end protection against lightning-induced surges on universal input (90–264 VAC). IC Role / Device Role / Timing Role: Secondary-side TVS on DC bus after bridge rectifier to protect bulk capacitor and PFC controller. Use Value: 44.4–54.3 V V_BR range ensures precise triggering above 36 V DC bus, avoiding nuisance conduction during normal ripple.

Switching Mode Power Supply (SMPS)

On-board DC/DC Converter

Use Scenario: Input stage protection against line surges and hot-swap transients in 48 V telecom rectifiers.

IC Role / Device Role / Timing Role: Unidirectional TVS placed between input capacitor and primary-side controller to clamp induced spikes before they reach PWM IC.

Use Value: Limits voltage excursion to ≤71.4 V during 400 W transients, preventing gate oxide damage to MOSFET drivers and maintaining regulation integrity.

Use Scenario: Protection of 5 V/3.3 V point-of-load regulators in industrial PLC backplanes.

IC Role / Device Role / Timing Role: Standoff-rated TVS on secondary-side output rail to absorb coupling noise from adjacent switching channels.

Use Value: 40 V V_WM allows safe operation with 36 V nominal input, while 1 μA leakage avoids loading low-current feedback networks.

Automotive Lighting Driver

Adapter Input Stage

Use Scenario: Overvoltage suppression on LED driver inputs exposed to 12 V/24 V vehicle battery transients.

IC Role / Device Role / Timing Role: Primary-line TVS absorbing load-dump pulses (ISO 7637-2 Pulse 5a) upstream of buck controller.

Use Value: 400 W rating handles 120 V/100 ms load dump energy; 150°C T_J max supports under-hood mounting near headlamp assemblies.

Use Scenario: AC-DC adapter front-end protection against lightning-induced surges on universal input (90–264 VAC).

IC Role / Device Role / Timing Role: Secondary-side TVS on DC bus after bridge rectifier to protect bulk capacitor and PFC controller.

Use Value: 44.4–54.3 V V_BR range ensures precise triggering above 36 V DC bus, avoiding nuisance conduction during normal ripple.

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Littelfuse SMAJ40A	Lower V_BR range (44.4–49.1 V), tighter tolerance; identical DO-214AC package and 400 W rating.	Preferred where tighter breakdown consistency is required for precision clamping in regulated 36 V systems.	Select SMAJ40A if V_BR uniformity across production lots is critical; SMAJ40C offers broader V_BR spread for cost-sensitive designs.
ON Semiconductor SMAJ40CA	Bidirectional variant (CA suffix); same V_WM/V_BR/V_C specs but symmetrical clamping in both polarities.	Required for AC-coupled or floating-rail protection where reverse polarity events must also be suppressed.	Choose SMAJ40CA only if bidirectional protection is mandated; SMAJ40C is optimal for standard unidirectional DC rail use.

Compared with SMAJ40A and SMAJ40CA, the SMAJ40C provides the broadest V_BR tolerance (44.4–54.3 V) among the three, making it suitable for cost-driven applications where exact clamping threshold is less critical than surge energy absorption and thermal robustness.

Availability

SMAJ40C is available at Aetrix Electronics and suitable for switching mode power supplies, automotive lighting drivers, and industrial DC/DC converters requiring stable component supply with full traceability and lifecycle management.

Supply support for SMAJ40C includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in high-reliability protection devices and power components.

The SMAJ series was developed specifically for automotive-grade transient suppression, emphasizing ISO 7637-2 compliance, high-temperature operation, and automated assembly compatibility in DO-214AC packaging.

FAQ

What is the polarity configuration of the SMAJ40C?

The SMAJ40C is a unidirectional TVS diode, with cathode marked by a band on the DO-214AC package. It conducts in forward bias (anode-to-cathode) and clamps in reverse bias when voltage exceeds its breakdown range of 44.4–54.3 V. This configuration makes SMAJ40C ideal for protecting DC power rails where polarity is fixed and reverse-voltage events are not expected.

Does the SMAJ40C meet automotive transient standards?

Yes, the SMAJ40C fully meets ISO 7637-2 requirements for Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnection/reconnection), and Pulse 3a/3b (capacitive coupled transients). Its 400 W peak pulse rating and 150°C junction temperature capability are validated for under-hood and ECU-level deployment, as confirmed in Taiwan Semiconductor's U2102 datasheet.

What is the maximum clamping voltage of the SMAJ40C under surge conditions?

The SMAJ40C clamps to a maximum of 71.4 V when subjected to its rated 5.6 A peak impulse current (I_PPM) under the standardized 10/1000 μs waveform. This value is guaranteed across the full operating temperature range and defines the upper voltage limit imposed on protected circuitry during transient events.

How does the SMAJ40C differ from the SMAJ40A variant?

The SMAJ40C has a wider breakdown voltage range (44.4–54.3 V) compared to the SMAJ40A (44.4–49.1 V), reflecting looser V_BR tolerance. Both share identical package, power rating, and clamping performance, but SMAJ40C is selected for cost-optimized designs where precise V_BR matching is unnecessary - unlike SMAJ40A, which targets tighter-clamp applications.

Is the SMAJ40C RoHS and halogen-free compliant?

Yes, the SMAJ40C is RoHS compliant and halogen-free per IEC 61249-2-21. Its molding compound meets UL 94V-0 flammability rating, and matte tin-plated leads comply with J-STD-002 solderability standards. These certifications are explicitly stated in the Taiwan Semiconductor U2102 datasheet for the SMAJ5.0–SMAJ188 family.

SMAJ40C Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Package/Case:: DO-214AC, SMA

Series:: SMAJ

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Zener

Unidirectional Channels:: -

Bidirectional Channels:: 1

Voltage - Reverse Standoff (Typ):: 40V

Voltage - Breakdown (Min):: 44.4V

Voltage - Clamping (Max) @ Ipp:: 71.4V

Current - Peak Pulse (10/1000µs):: 5.6A

Power - Peak Pulse:: 400W

Power Line Protection:: No

Applications:: General Purpose

Capacitance @ Frequency:: -

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DO-214AC (SMA)

SMAJ40C FAQ

1.How can I place an order for SMAJ40C through Aetrix?

Please submit a Request for Quotation (RFQ) for SMAJ40C on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SMAJ40C reliable?

The price and inventory of SMAJ40C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40C is usually 5 days.

3.What payment methods are accepted for SMAJ40C?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40C transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SMAJ40C?

SMAJ40C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SMAJ40C order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SMAJ40C?

For technical support, including SMAJ40C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40C requirements.

6.How does Aetrix verify that SMAJ40C is sourced from the original manufacturer or authorized distributors?

All SMAJ40C products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SMAJ40C meets industry standards.

7.What is the process for return or replacement of SMAJ40C?

All SMAJ40C units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40C, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SMAJ40C part is unused and in its original packaging.

Return procedure for SMAJ40C:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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